The present invention relates generally to magnetic resonance (MR) imaging and, more particularly, to a method and apparatus that enables a user to simultaneously view spatial and spectral data acquired from the same spatial slice of tissue an MR manual pre-scan.
When a substance such as human tissue is subjected to a uniform magnetic field (polarizing field B0), the individual magnetic moments of the spins in the tissue attempt to align with this polarizing field and precess about it in random order at their characteristic Larmor frequency. If the substance, or tissue, is subjected to a magnetic field (excitation field B1) which is in the x-y plane and which is near the Larmor frequency, the net aligned moment, or “longitudinal magnetization”, Mz, may be rotated, or “tipped”, into the x-y plane to produce a net transverse magnetic moment Mt. A signal is emitted by the excited spins after the excitation signal B1 is terminated and this signal may be received and processed to form an image.
When utilizing these signals to produce images, magnetic field gradients (Gx, Gy, and Gz) are employed. Typically, the region to be imaged is scanned by a sequence of measurement cycles in which these gradients vary according to the particular localization method being used. The resulting set of received NMR signals are digitized and processed to reconstruct the image using one of many well known reconstruction techniques.
Magnetic resonance imaging typically includes a patient-specific pre-scan calibration/setting of system center frequency, transmit pulse gain, fine center frequency and receive gain. When performing this multi-part procedure manually, an operator typically invokes separate pulse sequences for acquiring the center frequency data and object projection data. The operator is required to manually switch between these two modes and wait for any system software and MR physics steady state related delays before a new object projection plot or center frequency spectrum is displayed.
It would therefore be desirable to have a method and apparatus capable of reducing system software and MR physics steady state related delays caused by invoking separate pulse sequences for acquiring the center frequency data and object projection data.